Compressor



Oct, 13, 1925- 1,557,434

D. D. DEMAREST COMPRESSOR Filed Dec. 25, 1922 2 sheets-saw. 1

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Q U. DEMAREST COMPRES 5011 Filed 23 1922 2 Sheets-Siam??? 2 compressor, the power Patented Get. 13, 1925.-

UNITED STATES nanrnn DOUGLAS DEMARES'I',

0F MONTGLAIR, NEW JERSEY.

COMPRESSOR.

Application filed December 23, 1922. Serial No. 608,625.

To all whom it may concern: 7

Be it known that I, DANIEL DoUoLAs DuMAnnsT, a citizen of the United States, residing in Montclair, in the State of New Jersey, have invented certain new and use ful Improvements in Compressors, of which the following is a specification, reference being had to the accompanying drawing, forming a part hereof.

This invention relatesto compressors and motors of the rotary which the pistons move rectilinearly in cylinders which revolve about a common axis. It is well understood that a mechanism of this, type can be used either as a pump or being applied to the crank shaft and fluid being compressed in the cylinders by the movement of the pistons, or as a motor, fluid under pressure being supplied to the cylinders for the purpose of applying power through the crank shaft. The improvements in which the present invention consists are of equal advantage whether the mechanism be considered as a compressor or as a motor and while the invention is entitled as an improvement in compressors, it will be understood that such title is not restrictive of the invention so far as concerns the particular use to which the mechanism is applied. In accordance with the invention the cylinders are mounted rigidly on a rotatable carrier, preferably in diametrically opposite pairs, and the pistons are connected to a rotatable crank shaft the axis of which is eccentric with respect to the axis of rotation of the cylinder carrier. rangement secure material advantages. They make it possible to secure a mechanism of large volumetric capacity though light in weight and compact in form; a mechanism capable of running at high speed with a minimum of friction and vibration; a mechanism in which the number of revolutions of the crank shaft is greater than the number of reciprocations of the pistons, so that, when the mechanism is used as a compressor, a high speed motor can be directly connected to the crank shaft while the piston speed is kept within moderate limits a rotary mechanism in which clearance may be reduced to an absolute minimum so that the mechanism is capable of creating or employing high pressures without appreciable loss by leakage; a mechanism in which the mass of the revolving cylinders renders unreciprocating type, in

"This construction and a1 necessary the employment of a fly wheel, while the movement of the cylinders promotes cooling. The invention will be explained more fully hereinafter with reference to the accompanying drawings in which it is illustrated and in which- Figure 1 is a plan viewin-longitudinal, central section of a mechanism which embodies the invention in approved form.

Figure 2 is a view of the'same in elevation as seen from the right hand in Figure 1.

' Figure 3 is a detail view of a pair of connected pistons.

Figure 4 is a detail of the bearing and clamping members to be referred to.

Figure 5 is a schematic illustration of the movement of the pistons in a complete rotat ion.

In the embodiment of the invention represented in the drawings a complete mechanism is shown as supported on a suitable base or frame a which is provided at 7) with suitable clamping members in which are securely fixed cylindrical bearing mem bers c and (Z which furnish bearings at c and d for a crank shaft 6, the bearings 0 and at being aligned but eccentrically disposed in the cylindrical bearing members 0 and d. 011 the inwardly extended, cylindrical end portions of the bearing menr bers c and d is mounted for rotation :1 cylinder carrier f, which supports the cylinders 9, preferably, although not necessarily, arranged in pairs, the two cylinders of each pair being diametrically opposed. The cylinders may communicate directly at their open inner ends with the crank chamber f which is formed within the carrier and encloses the cranks c of the eccentrically disposed crank shaft 6. Each cylinder receives a piston 71, and the opposed pistons, if they are arranged in pairs, are rigidly connected by a common piston rod h which at its middle point engages the corresponding crank 0. Should the cylinders be not arranged in pairs then a guide for the end of the piston rod opposite the single cylinder, takes the place of the opposite cylinder and in the construction illustrated one of the cylinders may be regarded as a guide .for the piston rod. Each cylinder head,

when the mechanism is employed as a pump or compressor, 1S provided with an air intake 71 having a check valve as at k and with a discharge port if, also having a suitable check valve h. ports k are connected by pipes h, provided with unions as at h with an annular manifold a mounted to rotate freely on the reduced end of the bearing member (5 and communicating through ports (1 with a cored interior d of the bearing member to :Zvhich may be connected a discharge pipe For convenience in manufacture the pistons h are shown as connected to the common piston rod h by ball and socket joints, as at h but such a joint is not essential as the piston rod, so far as the operation of the mechanism is concerned, might be connected rigidly to the pistons.

It will be noted that suitable packing devices are provided, as at f, f and f, to prevent leakage.

To comprehend the operation of the mechanism it must be borne in mind that the cylinder carrier is rotatable, that the crank shaft is also rotatable and is eccentrically disposed with respect to the cylinder carrier, that the throw of each crank is equalto the eccentricity of the crank shaft with respect to the cylinder carrier and that, if the cylinders are arranged in pairs as shown, the pis tons are connected by a rigid rod which engages the corresponding crank, the piston and cylinder at one end of such rod acting as a guide so that the angular relation of the rod to the piston and cylinder at the other end is not varied. It will be understood that as many of the radial cylinders may be provided as the conditions of operation may require and that each pair of pistons is engaged with a corresponding crank, the several cranks being the shaft so as to accommodate the several pairs of cylinders. It will further be noted that the piston stroke, by reason of the fact that the piston carrier and the crank shaft are independently rotatable, is equal to four times the throw of the crank. It will further be observed that through the relation of the cylinder carrier and the crank shaft the rotation of the crank shaft produces rotation of the cylinder carrier and the rate of rotation of the crank shaft is greater than the rate of rotation of the cylinder carrier. That is to say, the rotation of the crank shaft tends to press the pistons against the cylinder walls and as the cylinder carrier floats on its bearings it offers no obstacle to the pressure of the pistons against the cylinder walls and therefore rotates freely. As will be noted, the fluid under pressure (or vacuum, as the case may be), is transferred from the revolving cylinder to the relatively stationary member, or vice versa, with a minimum opportunity for loss by leakage and with a minimum of loss lpy friction or wear between contacting suraces The several discharge a that shown in Figure distributed lengthwise of In Figure 5 successive positions of the pistonsh, h are represented and the theoretical rigid connection of opposite pistons by the rigid piston rod is indicated by the line It. Successive positions pin are indicated by the four small circles, one of which is marked 6. The eccentric relation of the crank shaft with relation to the cylinder carrier is indicated by the small circle marked e. The position 1 of this figure is the position which corresponds to 1 for the lowermost piston h whichis shown in Figure 1 as at the very beginning of its forward stroke. It will be borne in mind that the straight line 72., representing the rigid piston rod must always pass through the axis of the cylinder carrier f, the circular path of which is represented by the broken line.

also be borne in mind that the same straight line, in every position of the cylinders and of the crank pin, must intersect the axis of the crank pin as shown. To fulfill all of the conditions above stated it will be seen that as the cylinder and therefore the piston moves from the position 1 to the position 2, through 45, the axis of the crank pin moves from the position 1 to the position 2 or through 90. Again, as the piston moves from the position 1, to the position 3, or through 90, the crank pin moves from the position 1 to the position 3, or through 180. The same rule holds for successive positions and it will therefore be obvious that a one-quarter rotation of the crank of the crank It must shaft is accompanied by a one-eighth rota tion of the cylinder carrier, so that two rotations of the crank shaft accompany one rotation of the cylinder carrier and the angular velocity of the cylinder carrier is one-half that of the crank shaft.

Furthermore, since the distance of the piston from the crank pin is the same for all positions, and as, in position 1 of Figure 5, for example, the piston and the crank pin are on the same side of the axis of the carrier, while in position 3 the crank pin and. the piston are on opposite sides of the axis of the carrier, and since between these two positions of the crank pin is twice the throw of the crank pin, that is, is twice the length of the radius arm of the crank pin, the linear movement or stroke of the piston must be twice the distance between the two opposite positions of the crank pin or four times the throw or radius arm of the crank pin.

It will be understood. that various changes in details of construction and arrangement can be made to suit different conditions of use and that the invention, except as pointed out in the accompanying claims, is not limited to the particular construction shown and described herein.

I claim as my invention:

the linear distance tatable crank 1. In a mechanism of the character described, the combination of a rotatable cylin der carrier, a cylinder carried thereby, a rotatable crank shaft eccentrically disposed with respect to the cylinder carrier, a piston, a piston. rod engaging the crank of the crank shaft, and meansto guide the piston rod, all being constructed and arranged to permit reciprocation ofthe piston and rotation of the cylinder carrier.

2. In a mechanism of the character described, the combination of a rotatable cylinder carrier, a cylinder carried thereby, a roshaft eccentrically disposed with respect to the cylinder carrier, the length of the crank being equal to the eccentricity of the shaft with respect to the carrier, a piston, a piston rod engaging the crank of the crank shaft, and means to guide the piston rod, all being constructed and arranged to permit reciprocation of the piston and rotation of the cylinder carrier.

3. In a mechanism of the character described, the combination of a rotatable cylinder carrier, a cylinder carried thereby, a rotatable crank shaft eccentrically disposed with respect to the cylinder carrier, a piston and a piston rod engaging the crank of the Y crank shaft, and a guide for the piston rod to maintain the angular relation of the piston rod and piston.

supported by the carrier,

4. In a mechanism of the character described, the combination of a rotatable cylinder carrier, a cylinder carried thereby and having in its head an inlet and an outlet, a

rotatable crank shaft eccentrically disposed with respect to the cylinder carrier, a piston and a piston rod engaging the crank of the crank shaft, and a rotatable connection to the outlet ofthe cylinder.

5. In a mechanism of the character described, the combination of a rotatable cylin-' der, carrier, diametrically opposed cylinders a rotatable crank shaft eccentrically disposed with respect to the cylinder carrier, pistons and a common piston rod engaging the crank shaft.

6. In a mechanism of the chracter described, the combination of a rotatable cylinder carrier, diametrically opposed cylinders supported by the carrier, a rotatable crank shaft eccentrically disposed with respect to the cylinder carrier, piston rod engaging the crank shaft, the cylinders having in their respective heads an inlet and an outlet, and an annular rotatable manifold connected to the several cylinder outlets. 1

This specification signed this 19th day of December A. D. 1922.

DANIEL DOUGLAS DEMARES'I.

pistons, and a common 

